This invention relates in general to pressure sensors and in particular to an electrical connector for a pressure sensor having movable electrical contacts that compensate for the stack up of tolerances of connected components.
An anti-lock brake system (ABS) is often included as standard equipment on new vehicles. When actuated, the ABS is operative to control the operation of some or all of the vehicle wheel brakes. A typical ABS, which controls all four vehicle wheels, includes a plurality of normally open and normally closed solenoid valves which are mounted within a control valve body and connected to the vehicle hydraulic brake system. A separate hydraulic source, such as a motor driven pump, is included in the ABS for reapplying hydraulic pressure to the controlled wheel brakes during an ABS braking cycle. The pump is typically included within the control valve body while the pump motor is mounted upon the exterior of the control valve body. A pressure sensor mounted upon the control valve body monitors the pressure generated by the vehicle master cylinder.
It is also known to provide an ABS for the rear wheels only. Such a system is commonly referred to as a rear wheel anti-lock brake system (RWABS). Typically, RWAL does not include a motor driver pump, but utilizes the vehicle master brake cylinder as a source of pressurized brake fluid. While RWABS has a limited volume of pressurized brake fluid available during an ABS braking cycle, elimination of the pump and pump motor simplifies the system while reducing the cost thereof. plurality of solenoid coils associated with the solenoid valves and one or more wheel speed sensors for monitoring the speed and deceleration of the controlled wheels. Additionally, the control module is electrically coupled through a connector to the pressure sensor. The control module is typically mounted within a removable housing which is attached to the control valve body to form a compact unit which is often referred to as an ABS Electro-hydraulic Control Unit (ECU).
It is known to mount the coils for actuating the solenoid coils within the control module housing. Tubular sleeves which enclose the valve armatures extend from the valve body, forming a seal for the hydraulic brake circuit. When the control module housing is mounted upon the valve body, each of sleeves is received by an associated solenoid coil. Accordingly, the housing can be removed from the valve body for servicing of the control module electronics without opening the hydraulic brake circuit.
During vehicle operation, the microprocessor in the ABS control module continuously receives wheel speed signals from the wheel speed sensors and pressure signals from the pressure sensor. The microprocessor monitors the wheel speed signals and pressure signals for potential wheel lock-up conditions. When the vehicle brakes are applied and the microprocessor senses an impending wheel lock-up condition, the microprocessor is operative to actuate the pump motor, in a four wheel ABS. The microprocessor also is operable to selectively operate the solenoid valves in the valve body to cyclically relieve and reapply hydraulic pressure to the controlled wheel brakes. The hydraulic pressure applied to the controlled wheel brakes is adjusted by the operation of the solenoid valves to limit wheel slippage to a safe level while continuing to produce adequate brake torque to decelerate the vehicle as desired by the driver.
Referring now to the drawings, there is illustrated, in FIG. 1, a typical prior art pressure sensor 10. The sensor 10 includes a generally cylindrical base 12 having a central axial bore 14 formed therein. The sensor 10 is mounted upon a control valve body 16 with the central bore 14 communicating with a control valve passageway 18 that is connected to the brake system master cylinder (not shown). An O-ring 20 is mounted upon the exterior of the base 12 to provide a seal between the sensor 10 and the control valve body 16. The upper end of the bore 14 terminates in a diaphragm 22.
The base 12 carries a central sensor portion 24 which typically includes a strain gauge type pressure sensing device 26 that uses resistive technology arranged in a full or half bridge configuration. The pressure sensing device 26 is mounted upon the upper surface of the diaphragm 22. The sensor central bore 14 receives pressurized brake fluid that presses against the lower surface of the diaphragm 22. The pressurized brake fluid slightly deflects the diaphragm 22, generating strains within the diaphragm 22. The strains are detected by the pressure sensing device 26 and converted into an electrical pressure signal. When the pressure within the central bore 14 changes, additional strains are developed in the diaphragm 22 and are detected by the pressure sensing device 26.
The central portion 24 of the sensor 10 also can include a Printed Circuit Board (PCB) 28 which carries an electronic circuit 30 for conditioning the pressure signals generated by the pressure sensing device 26. While the sensor 10 has been described and illustrated as having a resistive strain gauge type of pressure sensing device 26, it will be appreciated that the sensor 10 also can include other types of pressure sensing devices, such as, for example, a capacitive type of pressure sensing device (not shown).
The pressure sensor 10 further includes a cylindrical outer housing 32 that carries a male electrical connector 34. The electrical connector includes a disc-shaped base 36 that is crimped into the upper end of the outer housing 32. As shown in FIG. 1, a pair of pin connectors 38 extend through the connector base 36. While two pin connectors 38 are shown in FIG. 1, it will be appreciated that the sensor 10 also can have more or less pin connectors. Alternately, blade connectors (not shown) may be utilized. The lower ends of the pin connectors 38 extend through the printed circuit board 28 and are electrically connected to the electronic circuit 30. A corresponding female connector 40 is mounted upon the bottom surface of a control module PCB 42. The female connector 40 includes a base portion 44 that carries a pair of female connector sleeves 45. A portion of each of the connector sleeves 45 extends through the control module PCB 42 and is electrically connected to conductive traces (not shown) deposited upon the upper surface of the PCB 42. As illustrated in FIG. 1, the upper ends of the pin connectors 38 extend into, and make electrical contact with, the sleeves 45. The control module PCB 42 is carried by a control module housing (not shown). As described above, the control module housing is removeably mounted upon the control valve body 16. Upon removal of the control module from the control valve body 16, the male and female connectors 34 and 40 are separated.
This invention relates to an electrical connector for a pressure sensor having movable electrical contacts that compensate for the stack up of tolerances of connected components.
As explained above, it is desirable to be able to remove the electronic control module from a control valve body. To enable removable, a two piece electrical connector is provided between the pressure sensor 10 mounted upon the control valve body 16 and the PCB 44 carried by the electronic control module. However, the lower portion of the electrical connector is rigidly attached to the pressure sensor 10 that is mounted upon the control valve body 16 while the upper portion of the electrical connector is attached to the PCB 44 that is carried by the electronic control module housing. Accordingly, the stack up of tolerances of the components could cause misalignment of the upper and lower portions, 40 and 34, of the electrical connector and thereby actually prevent assembly of the electronic control module onto the control valve body 16. Therefore, it would be desirable to provide an improved pressure sensor having a connector that could accommodate the stack up of component tolerances.
The present invention contemplates an electrical connector that includes a cylindrical outer housing having an inside diameter and an inner housing having a disc shaped base portion disposed within the outer housing. The inner housing base portion has a diameter that is less than the inside diameter of said outer housing so that the inner housing is movable relative to the outer housing. The connector also has at least one electrical conductor carried by the inner housing.
It is further contemplated that the electrical connector outer housing has an end that extends in an inward radial direction to form a flange with the flange defining an aperture in an end of the outer housing. The flange extends over a portion of the inner housing base portion to retain the inner housing within said outer housing. Also, the inner housing includes a conductor portion that extends axially from the inner housing base portion through the outer housing aperture with the conductor portion carrying the electrical conductor.
In the preferred embodiment, the outer housing is included in a pressure sensor. Additionally, a portion of flex circuit that carries at least one conductive trace, is included in the connector. The flex circuit has a first end electrically connected to the inner housing electrical conductor and a second end electrically connected to an electrical component in the pressure sensor.
The invention contemplates that the inner housing is movable in a generally perpendicular direction relative to the axis of the sensor outer housing.
The electrical connector also can include an annular spacer disposed within the sensor outer housing with the spacer slidably contacting the inner housing and cooperating with the outer housing retaining flange to retain the inner housing base portion within the sensor outer housing.
Alternately, a plurality of tabs can be formed in the sensor housing with the tabs extending inward toward the sensor outer housing axis. The tabs co-operate with the outer housing flange to retain the inner housing base portion within the sensor outer housing.
As another alternative structure, the inner housing base portion can include a plurality of tabs formed about the circumference of the base portion with the tabs extending in a radial outward direction from the base portion. The sensor outer housing would then include a plurality of slots formed therethrough that correspond to the base portion tabs. Each of the slots slidably receives one of the base portion tabs to retain the inner housing within the sensor outer housing.
Alternately, the sensor outer housing also can include a first plurality of tabs formed about an end thereof and a second set of tabs formed about the sensor housing end that are axially offset from the first set of tabs. The first and second sets of tabs slidably receive an edge of the base portion of the inner housing therebetween to retain the inner housing within the sensor outer housing.
It is contemplated that the connector is utilized with a pressure sensor that is included in an anti-lock brake system, a traction control system or a vehicle stability control system.